Approximately one-fourth of the 600,000 bridges in the United States require repair or total replacement. In many cases, the direct and indirect costs of detouring traffic as a result of the temporary loss of a bridge during construction can exceed the actual cost of the repaired or replaced structure. For example, full-lane closures in large urban centers or on highways with heavy traffic volumes can have a significant economic impact on commercial and industrial activities in the region. Even partial lane closures can have economic impact and safety issues. Because of the potential economic impact and safety issues, minimizing traffic disruptions is a high priority when planning bridge related construction projects.
The use of Accelerated Bridge Construction (ABC) uses innovative planning, design, materials, and methods to reduce construction time when building new, or replacing existing, bridges. ABC construction methods often utilize modular components that are partially or entirely built or cast off-site. Railing systems utilized on the edges or sides of bridges are an example of a construction method that utilizes modular components.
One method utilizes a modular railing system with components having a solid railing cast as part of the deck or roadway support. These modular components can be transported to the site to assemble a full railing. These combined rail and deck modular components are awkward to move and complex to place on-site. Another method utilizes a pre-cast solid rail that is transported to the site and attached to the on-site deck. This method requires post-tensioning of the rail to the deck to prohibit movement of the rail, which is time-consuming and adds expense.
Pre-fabricated rail components that are easy to transport and simple and cost efficient to install would reduce construction time. Such components would also align with the goals of ABC project planning.